Carbon Repair? (Sailboard mast?)

[Rich Young]

One frustration in my Melanesia build has been a dearth of suitable timber for the spars and outrigger poles in my area.  Trees around here tend to be dense and twisty, rather than long and slender.

So I was kind of excited when a friend offered me a broken windsurfing mast the other day.  It's about 16' long, in two 8' sections that join in the middle, and it's made of either carbon fiber or a glass/carbon mixture.

The damage is at the joint - the smaller piece sleeves over the larger one, and that sleeve is fractured.  My question is, can this be repaired, and if so, how?  (It's okay if it doesn't separate into two pieces anymore.) 

Also, how can I safely cut a 16' carbon tube down to the proper 13' length for my crabclaw rig?  It seems like cutting with a saw would lead to a lot of fraying and damage.

Thanks for any help you can offer,

--Rich

[clif high]

Rich

we are making  carbon fiber yard and  boom(24 feet each) and mast(16 feet) now for our advanced crab  claw rig. The technique is to make short carbon tubes of  4 to 6 feet and then join them using inner ferrules. The ferrules are simple to make using unidirectional carbon fiber.  We get our fabric from fiber glass supply locally (pacific nw of north america).

 

take a plastic tube that will be small enough to fit inside both pieces of the mast, and allow for enough room to wind your fabric around it plus a couple layers of plastic.

 

you will want your ferrule to be equally inserted into both segments, and to be a foot in on  both (at that length).

Actually to make inner ferrule, wrap plastic around piping of suitable diameter. Then spray with lubricant like silicon spray or cooking oil....

then put another layer of plastic wrap over first layer and its coating of lubricant,

then wet out the carbon fiber and carefully wrap around the plastic covered tube. THen wrap the wetted out carbon fiber now aound your  tube with release fabric like econoply or some very fine, thin nylon fabric. This release fabric lets you squeeze out the excess resin, and also allows for the ferrule to bond  to the inside of your mast at the break without having to sand it. Then hang the ferrule up by one end to cure for 3 days or so. YOu hang it to keep it straight and allow the excess resin to drain off. The plastic layers allow you to separate the carbon tube from your mandrel.

 

Make sure your ferrule has more wraps of carbon (is thicker in wall size) than your mast and it will be stronger.

 

To rebuild split carbon the best way is an inner ferrule and then a new outer sleeve (if required).

 

Cut carbon fiber tube  with a hack saw, and  not a band saw or jig saw which can both  go bad quickly.

 

Good luck. these tubes are certainly repairable. Before  expoying the ferrule in place rough up the inside of the tube with good grit paper.

clif

 

[Rogerio Martin]

Use a jigsaw with a fine toothed saw or a bow handsaw to cut the pipe.

Make a thinner tube carbon fiber or glass between the inside of each amendment at least 30cm on each side. use a plastic pipe as a mold and epoxy resin, not polyester (epoxi desmold in plastic), to do the tube.

Put it all together with polyester resin with chopped strand

I hope helped, my english is poor and google translate help, but also mystifying.

 

Roger